Motor operational currents for three-phase motors (standard values for squirrel cage motors) [t-head1-first]

Minimum fuse size for short-circuit protection of three-phase motors [t-head3]

The maximum size is determined by the requirements of the switchgear or overload relay.

The rated motor currents are for standard 1500 r.p.m. motors with normal inner and outer surface cooling.

D.O.L. starting:	Maximum starting current: 6 × rated current Maximum starting time: 5 sec.
/ starting:	Maximum starting current: 2 × rated current Maximum starting time: 15 sec. Motor overload relay in phase current: set to 0.58 × rated current.

Rated fuse currents for / starting also apply to three-phase motors with slip-ring rotors.

For higher rated currents, starting currents and/or longer starting times, larger fuses will be required.

This table applies to “slow” or “gL” fuses (VDE 0636).

In the case of low-voltage h.b.c. fuses (NH type) with aM characteristics, fuses are to be selected according to their current rating. [t-head3]

Motor rating						230 V						400 V
						Motor ­operation rated ­current		Fuse				Motor­ operation rated ­ current		Fuse
								Direct starting		/				Direct starting		/
kW		cos φ		η [%]		A		A		A		A		A		A
0.06 0.09 0.12 0.18		0.7 0.7 0.7 0.7		58 60 60 62		0.37 0.54 0.72 1.04		2 2 4 4		– – 2 2		0.21 0.31 0.41 0.6		2 2 2 2		– – – –
0.25 0.37 0.55 0.75		0.7 0.72 0.75 0.79		62 66 69 74		1.4 2 2.7 3.2		4 6 10 10		2 4 4 4		0.8 1.1 1.5 1.9		4 4 4 6		2 2 2 4
1.1 1.5 2.2 3		0.81 0.81 0.81 0.82		74 74 78 80		4.6 6.3 8.7 11.5		10 16 20 25		6 10 10 16		2.6 3.6 5 6.6		6 6 10 16		4 4 6 10
4 5.5 7.5 11		0.82 0.82 0.82 0.84		83 86 87 87		14.8 19.6 26.4 38		32 32 50 80		16 25 32 40		8.5 11.3 15.2 21.7		20 25 32 40		10 16 16 25
15 18.5 22 30		0.84 0.84 0.84 0.85		88 88 92 92		51 63 71 96		100 125 125 200		63 80 80 100		29.3 36 41 55		63 63 80 100		32 40 50 63
37 45 55 75		0.86 0.86 0.86 0.86		92 93 93 94		117 141 173 233		200 250 250 315		125 160 200 250		68 81 99 134		125 160 200 200		80 100 125 160
90 110 132 160		0.86 0.86 0.87 0.87		94 94 95 95		279 342 401 486		400 500 630 630		315 400 500 630		161 196 231 279		250 315 400 400		200 200 250 315
200 250 315 400		0.87 0.87 0.87 0.88		95 95 96 96		607 – – –		800 – – –		630 – – –		349 437 544 683		500 630 800 1000		400 500 630 800
450 500 560 630		0.88 0.88 0.88 0.88		96 97 97 97		– – – –		– – – –		– – – –		769 – – –		1000 – – –		800 – – –

Motor rating						500 V						690 V
						Motor ­operation rated ­current		Fuse				Motor ­operation rated ­current		Fuse
								Direct starting		/				Direct starting		/
kW		cos φ		η [%]		A		A		A		A		A		A
0.06 0.09 0.12 0.18		0.7 0.7 0.7 0.7		58 60 60 62		0.17 0.25 0.33 0.48		2 2 2 2		– – – –		0.12 0.18 0.24 0.35		2 2 2 2		– – – –
0.25 0.37 0.55 0.75		0.7 0.72 0.75 0.79		62 66 69 74		0.7 0.9 1.2 1.5		2 2 4 4		– 2 2 2		0.5 0.7 0.9 1.1		2 2 4 4		– – 2 2
1.1 1.5 2.2 3		0.81 0.81 0.81 0.82		74 74 78 80		2.1 2.9 4 5.3		6 6 10 16		4 4 4 6		1.5 2.1 2.9 3.8		4 6 10 10		2 4 4 4
4 5.5 7.5 11		0.82 0.82 0.82 0.84		83 86 87 87		6.8 9 12.1 17.4		16 20 25 32		10 16 16 20		4.9 6.5 8.8 12.6		16 16 20 25		6 10 10 16
15 18.5 22 30		0.84 0.84 0.84 0.85		88 88 92 92		23.4 28.9 33 44		50 50 63 80		25 32 32 50		17 20.9 23.8 32		32 32 50 63		20 25 25 32
37 45 55 75		0.86 0.86 0.86 0.86		92 93 93 94		54 65 79 107		100 125 160 200		63 80 80 125		39 47 58 78		80 80 100 160		50 63 63 100
90 110 132 160		0.86 0.86 0.87 0.87		94 94 95 95		129 157 184 224		200 250 250 315		160 160 200 250		93 114 134 162		160 200 250 250		100 125 160 200
200 250 315 400		0.87 0.87 0.87 0.88		95 95 96 96		279 349 436 547		400 500 630 800		315 400 500 630		202 253 316 396		315 400 500 630		250 315 400 400
450 500 560 630		0.88 0.88 0.88 0.88		96 97 97 97		615 – – –		800 – – –		630 – – –		446 491 550 618		630 630 800 800		630 630 630 630